upstream-doc/manglsl/mix.xml

   1 <?xml version="1.0" encoding="UTF-8"?>
   2 <!DOCTYPE book PUBLIC "-//OASIS//DTD DocBook MathML Module V1.1b1//EN"
   3               "http://www.oasis-open.org/docbook/xml/mathml/1.1CR1/dbmathml.dtd">
   4 <refentry id="mix">
   5     <refmeta>
   6         <refmetainfo>
   7             <copyright>
   8                 <year>2011</year>
   9                 <holder>Khronos Group</holder>
  10             </copyright>
  11         </refmetainfo>
  12         <refentrytitle>mix</refentrytitle>
  13         <manvolnum>3G</manvolnum>
  14     </refmeta>
  15     <refnamediv>
  16         <refname>mix</refname>
  17         <refpurpose>linearly interpolate between two values</refpurpose>
  18     </refnamediv>
  19     <refsynopsisdiv><title>Declaration</title>
  20         <funcsynopsis>
  21             <funcprototype>
  22                 <funcdef>genType <function>mix</function></funcdef>
  23                 <paramdef>genType <parameter>x</parameter></paramdef>
  24                 <paramdef>genType <parameter>y</parameter></paramdef>
  25                 <paramdef>genType <parameter>a</parameter></paramdef>
  26             </funcprototype>
  27         </funcsynopsis>
  28         <funcsynopsis>
  29             <funcprototype>
  30                 <funcdef>genType <function>mix</function></funcdef>
  31                 <paramdef>genType <parameter>x</parameter></paramdef>
  32                 <paramdef>genType <parameter>y</parameter></paramdef>
  33                 <paramdef>float <parameter>a</parameter></paramdef>
  34             </funcprototype>
  35         </funcsynopsis>
  36         <funcsynopsis>
  37             <funcprototype>
  38                 <funcdef>genDType <function>mix</function></funcdef>
  39                 <paramdef>genDType <parameter>x</parameter></paramdef>
  40                 <paramdef>genDType <parameter>y</parameter></paramdef>
  41                 <paramdef>genDType <parameter>a</parameter></paramdef>
  42             </funcprototype>
  43         </funcsynopsis>
  44         <funcsynopsis>
  45             <funcprototype>
  46                 <funcdef>genDType <function>mix</function></funcdef>
  47                 <paramdef>genDType <parameter>x</parameter></paramdef>
  48                 <paramdef>genDType <parameter>y</parameter></paramdef>
  49                 <paramdef>double <parameter>a</parameter></paramdef>
  50             </funcprototype>
  51         </funcsynopsis>
  52         <funcsynopsis>
  53             <funcprototype>
  54                 <funcdef>genType <function>mix</function></funcdef>
  55                 <paramdef>genType <parameter>x</parameter></paramdef>
  56                 <paramdef>genType <parameter>y</parameter></paramdef>
  57                 <paramdef>genBType <parameter>a</parameter></paramdef>
  58             </funcprototype>
  59         </funcsynopsis>
  60         <funcsynopsis>
  61             <funcprototype>
  62                 <funcdef>genDType <function>mix</function></funcdef>
  63                 <paramdef>genDType <parameter>x</parameter></paramdef>
  64                 <paramdef>genDType <parameter>y</parameter></paramdef>
  65                 <paramdef>genBType <parameter>a</parameter></paramdef>
  66             </funcprototype>
  67         </funcsynopsis>
  68     </refsynopsisdiv>
  69     <refsect1 id="parameters"><title>Parameters</title>
  70         <variablelist>
  71         <varlistentry>
  72             <term><parameter>x</parameter></term>
  73             <listitem>
  74                 <para>
  75                     Specify the start of the range in which to interpolate.
  76                 </para>
  77             </listitem>
  78         </varlistentry>
  79         <varlistentry>
  80             <term><parameter>y</parameter></term>
  81             <listitem>
  82                 <para>
  83                     Specify the end of the range in which to interpolate.
  84                 </para>
  85             </listitem>
  86         </varlistentry>
  87         <varlistentry>
  88             <term><parameter>a</parameter></term>
  89             <listitem>
  90                 <para>
  91                     Specify the value to use to interpolate between <parameter>x</parameter> and <parameter>y</parameter>.
  92                 </para>
  93             </listitem>
  94         </varlistentry>
  95         </variablelist>
  96     </refsect1>
  97     <refsect1 id="description"><title>Description</title>
  98         <para>
  99             <function>mix</function> performs a linear interpolation between <parameter>x</parameter>
 100             and <parameter>y</parameter> using <parameter>a</parameter> to weight between them. The return value
 101             is computed as follows:
 102             <inlineequation>
 103                 <mml:math>
 104                     <mml:mi>x</mml:mi>
 105                     <mml:mo lspace='2px' rspace='2px'>&sdot;</mml:mo>
 106                     <mml:mo stretchy='false'>(</mml:mo>
 107                     <mml:mn>1</mml:mn>
 108                     <mml:mo>&minus;</mml:mo>
 109                     <mml:mi>a</mml:mi>
 110                     <mml:mo stretchy='false'>)</mml:mo>
 111                     <mml:mo>+</mml:mo>
 112                     <mml:mi>y</mml:mi>
 113                     <mml:mo lspace='2px' rspace='2px'>&sdot;</mml:mo>
 114                     <mml:mi>a</mml:mi>
 115                 </mml:math>
 116             </inlineequation>.
 117         </para>
 118         <para>
 119             For the variants of <function>mix</function> where <parameter>a</parameter> is <constant>genBType</constant>,
 120             elements for which <parameter>a</parameter>[<emphasis>i</emphasis>] is <constant>false</constant>, the result for that
 121             element is taken from <parameter>x</parameter>, and where <parameter>a</parameter>[<emphasis>i</emphasis>] is
 122             <constant>true</constant>, it will be taken from <parameter>y</parameter>.
 123         </para>
 124     </refsect1>
 125     <refsect1 id="versions"><title>Version Support</title>
 126         <informaltable frame="topbot">
 127             #VARTABLECOLS#
 128                 <thead>
 129                     #FUNCTABLEHEADER#
 130                     <row>
 131                         <entry>mix (genType)</entry>#newin11#
 132                     </row>
 133                     <row>
 134                         <entry>mix (genDType)</entry>#newin40#
 135                     </row>
 136                 </thead>
 137             </tgroup>
 138         </informaltable>
 139     </refsect1>
 140     <refsect1 id="seealso"><title>See Also</title>
 141         <para>
 142             <citerefentry><refentrytitle>min</refentrytitle></citerefentry>,
 143             <citerefentry><refentrytitle>max</refentrytitle></citerefentry>
 144         </para>
 145     </refsect1>
 146     <refsect1 id="Copyright"><title>Copyright</title>
 147         <para>
 148             Copyright <trademark class="copyright"></trademark> 2011 Khronos Group.
 149             This material may be distributed subject to the terms and conditions set forth in
 150             the Open Publication License, v 1.0, 8 June 1999.
 151             <ulink url="http://opencontent.org/openpub/">http://opencontent.org/openpub/</ulink>.
 152         </para>
 153     </refsect1>
 154 </refentry>